Camera solver: take track offset into account

This helps in cases when it's needed to track a feature which
goes out of screen for a while to prevent jump of camera.

source/blender/blenkernel/intern/tracking.c

@@ -2551,7 +2551,8 @@ static struct libmv_Tracks *libmv_tracks_new(ListBase *tracksbase, int width, in
 
 			if ((marker->flag & MARKER_DISABLED) == 0) {
 				libmv_tracksInsert(tracks, marker->framenr, tracknr,
-				                   marker->pos[0] * width, marker->pos[1] * height);
+				                   (marker->pos[0] + track->offset[0]) * width,
+				                   (marker->pos[1] + track->offset[1]) * height);
 			}
 		}